Objective:

My proposed research will examine the molecular and cellular effects of environmental estrogens (EEs) on developing neuronal precursors and abnormally developed childhood brain tumors. I will be researching the effects of chemicals with hormone-like actions that occur both naturally in the environment as phytoestrogens, and as xenoestrogens, synthetic detergents or byproducts of plastic or manufacture. Understanding the effects that these agents have on gene expression and their physiological impact on proliferation, cell growth, cell death or metastasis will provide much insight into the effects of exposure.

I hypothesize that medulloblastoma (MD) cell growth and invasion are stimulated by the xenoestrogen bisphenol A (BPA) and the active soy-derived phytoestrogen equol. Two specific aims will be addressed in my research. I will determine the dose response characteristics of BPA and equol exposure on MD cell growth and invasion in culture, as well as examining these effects in vivo.

Approach:

Complete dose response curves (10-14 – 10-5 M) will be generated for each compound using a MD derived cell line under serum-free conditions. The proliferative effects of each compound will be determined by standard automated viability and proliferation assays. The dose responsiveness of cell migration will be determined using a modified Boyden transwell assay. For the in vivo studies, subcutaneous xenografts of the MD cell line will be established in young ovariectomized nude mice that are maintained on soy free diets. Tumor growth rate and volume will be monitored over time in the presence and absence of BPA and equol. At the end of the study period, detailed histological analysis, including a quantitative assessment of tumor cell invasion of non-malignant tissues will be performed.

Expected Results:

EEs have been shown to both mimic and antagonize the effects of endogenous estrogen in the developing brain. Previous results have shown that developing neuronal precursors respond to physiologically low concentrations of estrogen which can influence growth, viability, and programmed cell death of developing neurons. MD is a neuronal precursor-like brain tumor that is estrogen responsive. Exposure of this tumor to EEs will promote cell growth and invasion.

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.